A total solar eclipse on July 11 has the potential to give some
ground-based observers a stunning five-minute celestial show, but you'd almost
have to go to ends of the Earth to try and see it.

Solar eclipses occur when the moon gets between the sun and
Earth, blotting out some or all of the sun.

While the moon's dark cone of shadow (called the umbra) will
pass more than one-third of the way around the Earth during this solar
eclipse, virtually the entire ground track for the event falls over the remote
open ocean waters of the South Pacific. Land encounters will be very few and
generally far between.

(This graphic shows the ground track depicting where
this total eclipse of 2010 will be visible from and when.)

For astronomers, total solar
eclipses provide an opportunity to observe the pearly white corona, or
outer atmosphere, of the sun. They occur when the moon comes between the Earth
and the sun, completely obscuring the sun from our persepective.

The corona's brightness is only about one-millionth as
bright as sunlight, but when the moon completely obscures the visible
disk of the sun the corona shines out in magnificent splendor.

Today, we needn't wait for an eclipse to observe the corona
 astronomers use an instrument called the coronagraph, developed in 1930 by
the French astronomer, Bernard Lyot to observe the brighter, inner part of the
corona. But the beauty and awesomeness of a total eclipse are still unequaled
and is why some will travel long distances, to remote parts of the earth or on
the ocean to experience this glorious spectacle. [Solar
Eclipse Photos]

Story of the shadow

On July 11, the moon's shadow will touch down at local
sunrise about 870 miles (1,400 km) northeast of the North Island of New Zealand
and only three minutes later will sail through the Cook Islands, narrowly
missing the most populated (Rarotunga), but passing over the second largest
(Mangaia). Weather permitting, it should afford the 1,900 who live there a 3-minute,
18-second view of a totally eclipsed sun.?

After another 10 minutes, the umbra will glide
east-northeast past the Society Islands, barely missing the island of Tahiti by
a mere 15 miles (25 km). If you are stationed on the south coast of Tahiti Iti,
"Little Tahiti," you would see 99.3-percent of the sun's diameter blocked by the
new moon.

About five minutes later, the dark lunar shadow will take a
roughly 15-minute trek through French Polynesia into the Tuamotu Archipelago ?
the largest chain of atolls in the world, spanning an area roughly the size of western
Europe.

When the umbra departs the Tuamotus at around 18:48 UT, it
will spend the next 83 minutes traveling 2,000 miles (3,300 km) over the lonely
waters of the South Pacific. At 19:33:31 UT, literally in the middle of
nowhere, the total phase of the eclipse will reach its maximum duration: an
exceptionally long 5 minutes, 20 seconds.?

However, unless you're on a properly positioned boat or
aircraft, this prolonged view of the sun's corona will go unseen.

Easter Island in eclipse

But 35 minutes later, the shadow fortuitously makes a direct
hit on one of the world's most isolated islands: The legendary Easter Island,
known for its many hundreds of monolithic statues of various sizes that were
erected by its native Rapanui people.

At Hanga Roa (pop. 3,300)  the main town, harbor and
capital of Easter Island  totality will last 4 minutes. 41 seconds, which is
only 39 seconds shorter than the maximum. Here, totality will take place in the
early-afternoon, with the sun 40 degrees high above the north-northwest
horizon.

After departing Easter Island, the Moon's umbra will cross
another 2,300 mi (3,700 km) of open ocean before making its final landfall in
Patagonia. It will reach the rockbound coast of Chile, sweeps over the Andes
and into Argentina and just before sliding off the Earth's surface (at 20:50
UT), passes over? the town of El Calafate, where totality will last 2 minutes,
47 seconds, but with the sun only 1 degree above the horizon.

Chasing the solar eclipse

A number of tours and expeditions have been organized to
view this upcoming eclipse. As one would expect, considering the lunar shadow's
considerable interaction with the South Pacific, most of these are on cruise
ships.

There is an advantage of an eclipse cruise in that the
ship's mobility can be factored in, allowing for last-minute maneuvers to avoid
any possible unsettled weather that might otherwise obscure a view of the
darkened sun. Climate data is carefully scrutinized to determine where the best
possible weather might be found along the eclipse track.?

The best location appears to be near Hao Island in French
Polynesia, where typical cloud obscuration values register at around 45 percent.?

At Easter Island, this figure increases to 55 to 60 percent,
while at Mangaia it jumps to 65 to 70 percent while at El Calafate it registers
almost 80 percent.?

As discouraging as some of the figures are, however, keep in
mind that in the past there have been cases where places with excellent weather
prospects ended up with clouds while places with poor prospects ended up seeing
the eclipse.? As science fiction writer, Robert Heinlein (1907-1988) once
noted: "Climate is what you expect, but weather is what you get!"

Solar eclipse addict

The only guaranteed view of totality would be from a jet
aircraft.?

One in particular  a Skytraders Airbus A319LR/ACJ  will
not only rendezvous with the moon's shadow, but will actually race it thereby
prolonging the duration of totality for approximately 9 and a half minutes
while flying at an altitude of 40,000 feet.?

The person who has mapped out the circumstances for this
unusual flight is Dr. Glenn Schneider, an Astronomer at Arizona's
Steward Observatory, and the Project Instrument Scientist for the Hubble Space
Telescope's Near Infra-red Camera and Multi-Object Spectrometer.? He is also an
umbraphile; literally a "shadow lover", but properly applied,
one who is hopelessly addicted to the glory and majesty of total solar
eclipses.

"Those who have basked in the moon's shadow will know what I
mean without further explanation," Schneider writes. "Those who have not may
have difficulty in understanding that umbraphillia is not only an addiction,
but an affliction, and a way of life."

Schneider is indeed addicted to eclipses.?

He saw his first in 1970. July 11 will be his 29th total
solar eclipse.? He has spent nearly 82-minutes "basking" in the shadow of the
moon.? If you're interested in joining him on what he has billed as "EFlight
2010," you can contact him directly at: gschneider@as.arizona.edu

Joe Rao serves as an instructor and guest lecturer at New
York's Hayden Planetarium. He writes about astronomy for The New York Times and
other publications, and he is also an on-camera meteorologist for News 12
Westchester, New York.